Multilayer Substrate Core Laser Drilling Microvia Fabrication
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Solution Overview
Problem
Existing multilayer substrate core fabrication methods are costly and inefficient due to mechanical drilling, which is expensive and unsuitable for producing holes smaller than 150 microns, leading to high manufacturing costs and limitations in miniaturization.
Innovation Solution
The method involves laser drilling microvias through the insulating layer, followed by selective fast electroless plating to fill the vias, and using a semi-additive process for patterning, replacing the costly plated through hole structure with laser drilled microvias, allowing for smaller via sizes and pitches, and reducing processing time and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical drilling is used to create through holes, then the fabrication process can be completed with conventional methods, but the manufacturing cost becomes excessively high and holes smaller than 150 microns cannot be produced
Solution Approach 1:
The patent replaces mechanical drilling with laser drilling technology. The laser beam drills microvias through the insulating layer without mechanical contact, enabling production of holes smaller than 150 microns while reducing manufacturing costs. This substitution of mechanical system with optical/thermal system directly resolves the contradiction between manufacturing precision and ease of manufacture.
Solution Approach 2:
The patent changes the drilling method from mechanical to laser-based, altering the fundamental parameter of how holes are created. This parameter change enables precise control of hole dimensions down to sub-150 micron scales while maintaining cost-effectiveness through automated laser processing, thereby resolving the contradiction between small hole size capability and manufacturing cost.
2Reliability
If plated through hole structure is used, then electrical connectivity can be achieved, but the processing time and manufacturing cost increase significantly
Solution Approach 1:
The patent extracts the plugging step from the conventional plated through hole process. By using laser-drilled microvias that are selectively filled with conductive material only where needed (rather than plugging all through holes), the process eliminates unnecessary plugging operations, reducing processing time while maintaining electrical connectivity reliability through selective conductive filling.
Solution Approach 2:
The patent applies partial action by selectively filling only the necessary microvias with conductive material rather than performing complete plugging of all through holes. This partial filling approach maintains sufficient electrical connectivity for the design while significantly reducing processing time and material usage compared to complete plugging.
3Adaptability or versatility
If conventional core build-up process is used, then multilayer substrate can be fabricated, but the fabrication process becomes lengthy and complex
Solution Approach 1:
The patent segments the fabrication process into distinct stages: laser drilling of microvias, selective conductive filling, and semi-additive patterning. This segmentation allows each step to be optimized independently and simplifies the overall process control, reducing fabrication complexity while maintaining design flexibility for multilayer substrate configurations.
Solution Approach 2:
The patent inverts the conventional approach by using semi-additive patterning instead of traditional subtractive etching methods. This inversion allows for greater design flexibility in creating complex interconnect patterns while simplifying the fabrication process through additive manufacturing techniques that build up conductive features directly on the substrate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces manufacturing costs, enables miniaturization, and provides high alignment accuracy and throughput, allowing for smaller form factors and more flexible core routing configurations with lower costs and improved design performance.
Implementation Method 1
laser drilling a first set of via openings through the starting insulating layer
Implementation Method 2
filling the via openings with a conductive material to provide a first set of conductive vias
Data Source
AI summary
A method of fabricating a substrate core structure, and a substrate core structure formed according to the method. The method includes: laser drilling a first set of via openings through a starting insulating layer; filling the first set of via openings with a conductive material to provide a first set of conductive vias; providing first and second patterned conductive layers on opposite sides of the starting insulating layer; providing a supplemental insulating layer onto the first patterned conductive layer; laser drilling a second set of via openings through the supplemental insulating layer; filling the second set of via openings with a conductive material to provide a second set of conductive vias; and providing a supplemental patterned conductive layer onto an exposed side of the supplemental insulating layer, the second set of conductive vias contacting the first patterned conductive layer and the supplemental patterned conductive layer at opposite sides thereof.